Saturday, January 23, 2016

FEATURED | CZ-5 and CZ-7 to Make Debut Flight in 2016

China’s
new-generation space launchers, Chang Zheng-5 (CZ-5) and Chang Zheng-7 (CZ-7),
will both make their debut flights in 2016. During his recent interview with
the China News Service, Lei Fanpei, Chairman of the China Aerospace Science
& Technology Corporation (CASC), revealed that CZ-7 will make its debut
flight in June this year, followed by the CZ-5 in late September or early
October. However, he did not disclose what payloads, if any, will fly on these
missions.

Ready To Fly:

After decades of
incremental improvements to its existing launch capabilities, the Chinese space
programme is currently undergoing a major technological overhaul. This will
eventually see the construction of new spacecraft and rocket fabrication
facilities in Tianjin and a new space launch centre on the southern island of
Hainan, as well as the introduction of an entire family of more capable launch vehicles burning non-toxic, non-polluting liquid propellants. Once fully
operational, these new elements will greatly increase China’s future space
capabilities.

A ground testing
vehicle of the CZ-7 launcher was delivered to the Hainan Space Launch Centre in
late 2014 for an all-system launch simulation drill. Welding of the propellant
tanks for the first flying CZ-7 commenced in April 2015, and the assembly of
the launch vehicle designated CZ-7-Y1 is currently underway at the rocket
fabrication facility in Tianjin. Initially the rocket will be used to launch
the Tianzhou cargo vehicle. A certain number of unmanned missions will need to
be achieved to fully verify the launcher’s design, before it can be adopted for
manned missions.

The all-system
launch simulation drill of the CZ-5 using a ground testing vehicle commenced at
Hainan in September 2015 and is expected to complete in February 2016.
Construction of the four strap-on boosters began at the Shanghai Academy of
Spaceflight Technology (SAST) in November 2015, and the assembly of the flying
CZ-5 vehicle at the Tianjin rocket fabrication facility is underway.

Question remains
as whether the two missions will carry any payload. The Chinese aerospace
industry has a tradition to carry fully operational payload on debut flights of
its Chang Zheng series launchers, but neither of the two new launchers will
have their intended payload ready for flight in 2016. The first Tianzhou
vehicle is scheduled for launch sometime in late 2017 to perform an in-orbit
resupply mission with the Tiangong 2 space laboratory module, due for launch in
2016. Similarly, the first confirmed payload for the CZ-5 launcher is the
Chang’e 5 lunar sample return mission, currently scheduled for 2018. It is
therefore possible that a mock-up of the intended payload will fly on these
missions.

CZ-7

The CZ-7 is a
medium-lift orbital launcher developed by China Academy of Launch Vehicle
Technology (CALT). Development of the launcher commenced in 2010. Initially the
rocket will be used to launch the Tianzhou cargo vehicle from Launch Complex
201 in the newly-built Hainan Space Launch Centre. A man-rated CZ-7 has been proposed
and will be introduced after the unmanned variant has achieved a certain number
of flights in order to fully validate its design and demonstrate its
reliability and safety.

The basic
variant CZ-7 is in a configuration of two-stage core vehicle with four strap-on
liquid rocket boosters, powered by the newly developed YF-100 and YF-115 liquid
rocket engines, both burning kerosene as fuel and liquid oxygen (LOX) as
oxidiser. The entire launch vehicle stack is 53.1 m in length, with a total
launch mass of 594 t and a launch thrust of 7,200 kN (734 t). The payload
fairing is 4.2 m in diameter. The launcher will be capable of delivering 13,500
kg payload to a 200 x 400 km orbit inclined at 42°, or 5,500 kg payload to a 700
km sun-synchronous orbit (SSO).

CZ-5

The CZ-5 is
China’s new generation heavy-lift space launcher, comparable in performance to
the European Ariane 5 and the U.S. Delta IV Heavy. The launcher is designed to
loft large commercial satellites, space station modules, and deep space probes.
The CZ-5 programme gained governmental approval in June 2004, with the aim to
introduce a heavy-load orbital launch vehicle capable of delivering 14 tonnes
of payload to the geostationary transfer orbit (GTO), or 25 tonnes to the low
Earth orbit (LEO). The primary contractor is CALT, with the participation of
SAST to produce some components of the rocket.

The CZ-5 uses a
5 m diameter core stage powered by two LOX/LH2 YF-77 engines, each rated at
509.6 kN at sea-level. The four 3.35 m diameter strap-on boosters are each
powered by two LOX/Kerosene YF-100 engines, each rated at 1,179 kN. The upper
stage on the core vehicle is powered by two LOX/LH2 YF-75D engines. This
configuration is used for GTO launch missions, with a maximum payload capacity
of 14 t. The payload fairing is 5.2 m in diameter and 12.5 m in length. The
CZ-5B variant without the upper stage will be used to launch modules of the space station Tiangong, with a LEO payload capacity of 25 t.

Space
Infrastructure

So far, the
Chinese space programme has been relying on the CZ-2/3/4 series of rocket launchersintroduced in the 1970s—90s for its orbital launch missions. All of
these launchers were essentially derived from a single rocket design — the
liquid-fuel DF-5 (CSS-4) intercontinental ballistic missile (ICBM) that first
flew in 1971. The first-stage of the rocket is powered by a cluster of four
parallel YF-20 rocket motors (collectively known as YF-21), each producing 75 t
(740 kN) of thrust at take-off. By adding four strap-on boosters and/or upper
stages, the rocket can deliver up to 9.5 t payload to LEO or 5,500 kg to GTO.

The payload
capability of the current generation of Chang Zheng space launchers has reached
a ceiling due to a single factor of logistics: as China’s three existing launch
sites are all far inland, launch vehicle components have to be transported from
their factory to launch sites by railway. The size of the launcher is limited
to 3.35 m in diameter and about 14 m in length. Any design bigger than these
dimensions will not fit through the railway tunnels. In addition, a rocket with
high length-to-diameter ratio also brings challenges to its flight control
system.

To break this
limitation, China has completely overhauled its space infrastructure, which
involves the construction of a new rocket fabrication and testing facility in
the eastern coastal city of Tianjin and a new coastal launch centre on the
Hainan Island in southern China. Rocket boosters built in the Tianjin facility
will be transported by specially designed cargo ships via a sea route to the
launch centre. This approach not only eliminates the limitations in rocket
size, but also brings additional benefits in downrange safety and launch
dynamics due to the launch centre’s coastal location and its proximity to the
Earth Equator (19° N).